This article documents the expansion of college education in the United States and examines to what extent the increase in the number of college graduates may have lead to a decline in the average quality of college graduates. Using the 1940-90 Census, we compare across birth year cohorts with varying levels of college completion. We find some weak evidence that college graduate men from highly educated cohorts earn a relatively smaller wage premium even controlling for the relative supply effect. However, these cohort quality effects account for only a small fraction of the recent fluctuation in the college wage premium.